In a conventional TV wall system, the corresponding position and enlargement scale of each display device must be adjusted individually and manually so as to make the image corresponding to the image signal capable of being displayed correctly. However, adjusting each display device in a manual manner is quite complicated and may cause errors, and consequentially, some or all of these display devices may not display images correctly.
Thus, a conventional TV wall system equipped with sensors in each display device is developed. FIG. 1 is a schematic diagram of a conventional TV wall system. As shown in FIG. 1, each one of the display devices D1˜D9 has four sensors T1˜T4, which are respectively installed on the four edges of each display device. Through the aforementioned sensor arrangement on each one of the display devices D1˜D9, each sensor can only transmit signals to or detect one adjacent sensor. For example, the sensor T4 in the display device D3 can only transmit signals to or detect signals from the sensor T1 in the display device D6 and the sensor T3 in the display device D3 can only transmit signals to or detect signals from the sensor T2 in the display device D2. Thus, once the display devices D2, D6 are out of order or malfunctioning, the display device D3 cannot receive signal normally and consequentially the display device D3 is not able to display a respective part of an image correctly.